Saddle shaped deflection coil

ABSTRACT

A saddle type deflection coil for a cathode ray tube has cross sections, taken in planes perpendicular to a first axis corresponding to the longitudinal central axis of the cathode ray tube, which each consists of a pair of half sectional portions symmetrical about a second axis perpendicular to the first axis, each of the half sectional portions having an outer curved margin formed by an arc of a circle centered at the first axis and an inner margin having a curved part formed by an arc of another circle also centered at the first axis and a straight part extending from the curved parallel with the second axis. An apparatus for winding a saddle type deflection coil includes male and female members which, when mated, form a cavity into which the deflection coil mentioned as above is wound, whereby it becomes much easier to manufacture the coil winding apparatus and the deflection coils wound by the apparatus are of uniform quality and have good characteristics.

United States Patent lshikawa June 10, 1975 1 1 SADDLE SHAPED DEFLECTIONCOIL [751 Inventor: Yoji lshikawa, Saitama, Japan [73] Assignee: SonyCorporation, Tokyo, Japan [22] Filed: Aug. 6, 1974 [21] Appl. No.:495.293

Primary ExaminerG. Harris Attorney, Agent, or Firm-Lewis H. Eslinger;Alvin Sinderbrand [57] ABSTRACT A saddle type deflection coil for acathode ray tube has cross sections, taken in planes perpendicular to afirst axis corresponding to the longitudinal central axis of the cathoderay tube, which each consists of a pair of half sectional portionssymmetrical about a second axis perpendicular to the first axis, each ofthe half sectional portions having an outer curved margin formed by anarc of a circle centered at the first axis and an inner margin having acurved part formed by an arc of another circle also centered at thefirst axis and a straight part extending from the curved parallel withthe second axis. An apparatus for winding a saddle type deflection coilincludes male and female members which, when mated, form a cavity intowhich the deflection coil mentioned as above is wound, whereby itbecomes much easier to manufacture the coil winding apparatus and thedeflection coils wound by the apparatus are of uniform quality and havegood characteristics.

4 Claims, 17 Drawing Figures SHEET PATENTEDJUH 10 I975 PATENTEU JUN I 0I975 SHEET I I I I Z6 I I (M120 Baz 40 60 50 1 SADDLE SHAPED DEFLECTIONCOIL BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to a saddle type deflection coil for a cathode raytube and its winding apparatus.

2. Description of the Prior Art A saddle type deflection coil is widelyused for a cathode ray tube of a conventional television receiver andmany improvements have been proposed in the prior art to enhance thequality of such a deflection coil However, it was usually necessary toprovide the conductor windings of the deflection coil with a complex andprecisely arranged distribution in order to get a deflection coil ofgood quality. Therefore it was also necessary to make the apparatus forwinding the deflection coil both complex and precisely formed.

Such complex and precise structures of the deflection coil and itswinding apparatus are relatively expen sive and make it difficult to getuniform deflection coils when the latter are mass produced using severalof such winding apparatus.

OBJECTS OF THE INVENTION Accordingly, it is an object of this inventionto provide an improved and novel saddle type deflection coil.

It is another object of this invention to provide a novel saddle typedeflection coil. the structure or con figuration of which is simplified.

It is a further object of this invention to provide a novel saddle typedeflection coil in which the distribution of the conductor windings issimplified.

It is a still further object of this invention to provide a deflectioncoil winding apparatus of simple structure for winding the improved andnovel saddle type deflection coil.

SUMMARY OF THE INVENTION The saddle type deflection coil of thisinvention has cross sections. taken in planes perpendicular to a firstaxis corresponding to the longitudinal central axis of the cathode raytube, which each consist of a pair of half sectional portionssymmetrical with reference to a second axis perpendicular to the firstaxis, and each of the half sectional portions has an outer curved marginformed by an arc of a circle centered on the first axis, an inner marginhaving a curved part formed by an arc of another circle centered on thefirst axis and a straight part extending from the curved part parallelwith the second axis.

The winding apparatus for producing the saddle type deflection coilaccording to this invention includes a female member and a male member.Each cross section of the female member. taken on a plane perpendicularto a first axis corresponding to the longitudinal central axis of acathode ray tube, consists of a pair of half sectional portionssymmetrical with reference to a second axis perpendicular to the firstaxis, and each of the half sectional portions includes inner curvedmargin formed by an arc of a circle centered on the first axis. Eachcross section of the male member. taken on the same plane perpendicularto the first axis. consists of a pair of half sectional portionssymmetrical with reference to the second axis, and each of the halfsectional portions includes an outer margin having a curved part formedby an arc of another circle also centered on the first axis and astraight part extending from the curved part parallel with the secondaxis.

This invention may be better understood however when the followingdetailed description is read in connection with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a simplified sideelevational view of a representative deflection coil of the prior art.

FIGS. ZA-ZG are cross sectional views taken on the planes perpendicularto the Z. axis at points Z. Z,. in FIG. 1.

FIG. 3 is a graph showing the distribution of conductor windings atvarious planes corresponding to FIGS. 2A2G.

FIG. 4 is a partial cross sectional view of a winding apparatus forproducing the deflection coil of the prior art.

FIG. 5 is a schematic end elevational view of the deflection coilwinding apparatus shown in FIG. 4, with the male and female members ofsuch apparatus being shown in full and broken lines, respectively.

FIG. 6 is a graph to which reference will be made in explaning thedistribution of conductor windings of the deflection coil according tothe present invention as compared with that of the prior art.

FIG 7 is a partial cross sectional view of a defelection coil accordingto the present invention.

FIG. 8 is a partial cross sectional view of a deflection coil windingapparatus according to the present invention.

FIG. 9 is a schematic end elevational view similar to that of FIG. 5,but showing the coil winding apparatus of FIG. 8.

FIG. 10 is a simplified perspective view of the male member of thedeflection coil winding apparatus according to the present invention.

FIG. 11 is a graph similar to that of FIG. 3, but which shows thedistribution of conductor windings of the deflection coil according tothe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1 whichshows a typical saddle type deflection coil according to the prior art,it will be seen that the abscissa or Z-axis is parallel with thelongitudinal central axis of a cathode ray tube (not shown) of atelevision receiver, on which the saddle type deflection coil 1 ismounted, and is directed toward the screen of the cathode ray tube. Thecross sections of the deflection coil 1 in planes passing through pointsZ to Z. on the Z-axis and which are perpendicular to theaxis, that isparallel to the ordinate or Y-axis, are shown in FIGS. 2A to 2G,respectively. In each of FIGS. 2A to 2G, the abscissa or X-axis isperpendicular to both the Y-and Z-axes.

It will be seen that each of the cross-section shown in each of FIGS. 2Ato 20 consists of a pair of arc-shaped half sectional portions 5A and 5Bwhich are symmetrical with respect to the Y-axis. The half sectionalportions 5A and 5B are filled with a large number of conductor windingsdirected from rear to front of the sheet of FIGS. 2A to 2G. If the innerradius of the arc-shaped half sectional portions 5A and 5B is taken asRin. its angle from the left side of the X-axis is taken as 8 and thethickness of each of the section 5A and 58 on the extension of theradius Rin is taken. as d, the thickness d is generally selected tosatisfy the following expression:

d D cos"9 In the above expression, as the plane of the section is movedfrom point Z to point Z that is, from FIG. 2A to FIG. 2G, the value ofthe factor D gradually becomes smaller, while the value of the factor ngradually become greater. That is, with the prior art saddle typedeflection coil the thickness d is precisely controlled by the factorsD. n and 6. Such a precise control is necessary to compensate for orcorrect a raster distortion such as a so-called pincushion distortion,misconvergence and so on ofthe cathode ray tube in beam deflection.Since such a compensation or correction is well known in the art, itsdetailed description will be omitted for the sake of brevity.

The relationships between the thickness d and the angle 6 for each ofthe cross sectional portions A and SB shown in FIGS. 2A to 2G are shownby the curves 2A to 2G on FIG. 3.

If the inner and outer curves of the half cross sectional portions 5Ashown in FIGS. 2A to 2G are taken as p, and p and the inner and outercurves of the right half cross sectional portions 58 shown in FIG. 2A to2G are taken as q, and q it can be said that the saddle type deflectioncoil 1 shown in FIG. I is restricted in the distribution of conductorwindings by the curved inner surface which is formed by a number ofcontinuous curves p,, the curved outer surface which is formed by anumber of continuous curves p the curved inner surface which is formedby a number of continuous curves q and of the curved outer surface whichis formed by a number of continuous curves q In order to obtain theabove inner and outer surfaces which define the distribution ofconductor windings, a coil winding apparatus 10 used in the prior arthas a half cross sectional configuration as shown on FIG. 4 at the planewhich corresponds to the poane of the view on FIG. 2C. The coil windingapparatus 10 consists of a male member 10A with a predetermined outersur face N and of a female member 10B with a predetermined inner surfaceM opposing the outer surface N. The outer surface N of the male member10A is formed of a curved surface having a radius r extending from acenter or point S, at the intersection of the X-Y axes in FIG. 4, whilethe inner surface M of the female memher 108 is formed of a curvedsurface having a radius R extending from a center or point S which isspaced from the point 5, by Ar in the left direction of the X- axis andAy in the downward direction of the Yaxis. Thus, between the male andfemale members 10A and 108 there is formed a cavity or clearance 12whose thickness dis reduced as the winding angle 6 increases. Therefore,if conductor windings are wound to fill the cavity 12, a coil with thecross section similar to that shown in FIG. 2C is obtained.

FIG. 5 shows a schematic or simplified end elevational view of the coilwinding apparatus 10 which is used to form the deflection coil 1 havingthe cross sections shown in FIGS. 2A to 2G. In FIG. 5, the male member10A is shown by a solid line, while the female member 108 is shown by abroken line It will be seen that the outer surface N of male member 10Ais defined by a series of curves N -N The radius r of the outer curves N-N which form the outer surface N, has its center at the crossing point8, and increases gradually anti cciiunuously in the directionperpendicular to the plane of the sheet of the drawing (from rear tofront of the Z-axis in FIG. I). In short, the radius r is expressed by afunction of Z and the minimum inner curve N is determined by the minimumvalue r of the radius r, while the maximum inner curve N is determinedby the maximum value UI the radius r. If outer curves with the radiusfrom r to r are formed continuously in the Zaxis direction. an outersurface N which is changed in accordance with a curve of second degreeis obtained. The curve of second degree is predetermined to coincidewith the curved surface of the funnel portion of the cathode ray tube.The X- and Y-axes are used as reference or center axes for forming themale member 10A.

The inner surface M of the female member 108 is shown to be formed of aseries of curves M M The radius R of the minimum inner curve M has itscenter points 5 and S deviated from the Y- and X-axes by A r and A andthe radius R of the maximum inner curve M has its center points S and Sdeviated by Ar and Ay from the points S and S to form the inner curvewith the radius R Thus, the inner surface M is formed of a series ofinner curves M,-M whose radii have their centers changed gradually andcontinuously from the point S to the point S and from the point S to thepoint S Accordingly, when the female member 108 is worked, it isnecessary to shift the working reference or center axis.

In using coil winding apparatus 10, the latter is rotated in such amanner that conductor windings are supplied to the air gap or cavity 12formed between the outer surface N ofthe male member 10A and the innersurface M of the female member 108, and the rotation of the coil windingapparatus 10 is continued till the cavity 12 is filled with theconductor windings. Thus, there is obtained the deflection coil 1 withthe cross sections shown in FIGS. 2A to 2G. The driving mechanism forthe coil winding apparatus 10 is well known in the art, so that itsdescription will be omitted for the sake of brevity.

When the electron beam of the cathode rays tube is deflected by thedeflection coil 1 formed as described above, it is known, that asubstantial improvement in the various raster distortions such asmisconvergence, pincushion distortion or the like, requires relativelygreat difference betweem the distribution of conductor windings of thedeflection coil 1 at its rear and front ends considered in the Z-axisdirection or the longitudinal central axis of the cathode ray tube.However, in order to greatly change the distribution of conductorwindings, it is required that the working reference or center axis usedin the production of the female member 108 be shifted through relativelylarge distances, as described in connection with FIG. 5. Accordingly,difficulties are encountered in forming the inner surface of the femalemember 108. Therefore, in order to manufacture the deflection coil 1which has a great change in the distribution of conductor windingsbetween its front and rear ends it is necessary to either manually shapethe inner surface M of the respective female member 1013 or to form suchsurface with a computer controlled machine. In either case, the coilwinding apparatus 10 is expensive and, if shaped manually, it isdifficult to mass produce large numbers of the deflection coils using amember of the coil winding apparatus as achievement of the same contourson the manually shaped inner surfaces of such apparatus is verydifficult. As a result, the above mentioned misconvergence or distortioncan not be sufficiently improved by the previously existing deflectioncoils.

An embodiment of the present invention will be now described withreference to FIGS. 6-11.

Since the prior art deflection coil 1 is selected to have the thicknessto winding angle relation of d=Dcs 6, the thickness distribution of thedeflection coil 1 at the cross section shown in. for example, FIG. 2C,is shown in FIG. 6 by a solid line curve 21. However, a novel deflectioncoil 20 according to the present invention, which will be described indetail below and which has a typical section as shown on FIG. 7, isprovided with a cross sectional area the same as that of the prior art,but with the distribution of conductor windings within such area beingentirely from that represented by the curve 21, as follows. With thepresent invention, the distribution of the conductor windings isdecreased in thickness up to a certain winding angle 60, but is constantin thickness at winding angles exceeding the angle 6 as is indicated inFIG. 6 by a dotted line curve 22. The cross section of the deflectioncoil 20 according to the present invention shown in FIG. 7 correspondsto that of the prior art coil 1 shown on FIG. 2C.

The cross section shown in FIG. 7 is referenced to the X-and Y-axes asin the case of FIGS. 2A to 2G. The deflection coil 20 consists of a pairof half section portions 23A and 233 which are defined by outer andinner margins 24 and 25. The outer margin 24 is curved and is formed bya first arc with the radius R whose center is at the intersection O ofthe X and Y axes. The inner margin 25 is formed with a straight part 250parallel to the Y-axis between the values 0 and 6,, of the winding angle0, and a curved part 25b formed by an arc with the radius r whose centeris at the intersection 0 over the winding angle greater than 0 In thiscase, the angle 0,, and the radii r and R are so selected that the areasof the half sectional portions 23A and 23B are equal to those of thehalf sectional portions A and 513 shown in FIG. 2C.

FIG. 8 shows in cross section a coil winding apparatus 30 according tothe present invention which is suitable for making the deflection coilwith the section shown in FIG. 7. In FIG. 8, reference numeral 30Aindicates a male member which has an outer surface 26 corresponding tothe inner margin shown in FIG. 7, and reference numberal B indicates afemale member which has an inner surface 27 corresponding to the outermargin 24 shown in FIG. 7. As shown in FIG. 8, the inner surface 27 ofthe female member 3013 is formed as an arc with the radius R thereofhaving its center at the center 0 of the are which is used for defin ingthe curved part by the outer surface 26 of the male member 30A.

FIG. 9 is a simplified or schematic end elevational view of the coilwinding apparatus 30. In FIG. 9, the male member 30A is shown by a solidline, while the female member 308 is shown by a broken line. The outersurface 26 of the male member 30A and the inner surface 27 of the femalemember 308 are formed continuously in the direction of the Z-axis whichcorresponds to the longitudinal central axis of the cathode ray tube asmentioned above. and their centers are positioned at the intersectionpoint 0 of the Y- and X- axes.

As may be apparent from a comparsion of FIG. 9 with FIG. 5, the femalemember 303 of the coil winding apparatus 30 of the present invention issimplified as compared with the female member 108 of the prior art coilwinding apparatus 10. More specifically, with the prior art femalemember 108 the center or reference point for forming the inner surface Mmust be shifted by Ax and Ay from the intersection O of axes X and Y,while with the female member 303 of the present invention the centerpoint of the inner surface 27 with respect to the Y-and X-axes coincideswith the center point 0. In other words, when the female member 30b ofthe present invention is manufactured, there is no need to move thereference or center point with respect to the Y-and X-axes. Hence, thefemale member 308 can be obtained easily and precisely.

The configuration or contour changes of the outer surface 26 of the malemember 30A and the inner surface 27 of the female member 30B will now bedescribed. The outer and inner surfaces 26 and 27 are widened graduallyin the direction toward the front end of the respective coil inaccordance with the configuration of the funnel portion of the cathoderay tube. The radius R of the inner surface 27 of the female member 308is increased gradually from R, to R while the radius r of the part 25bouter surface 26 of the male member 30A is increased gradually from r,to r to form the curved part 25b. In this case, the straight part 250 isformed in accordance with the angle range 0, 6 which increases graduallyin the Z-axis direction. Thus, the main portion of the male member 30Ais formed as shown in FIG. 10, in which reference numbered 29 indicatesa concave portion which may engage with a convex portion 31 (FIG. 9) ofthe female member 30B. The distribution of conductor windings of thedeflection coil 20 formed by the coil winding ap paratus 30 consistingof the male and female members 30A and 30B is shown in FIG. 11. In orderto be compared with the prior art distribution shown in FIG. 3, FIG. 11shows the distribution at the cross sections of the deflection coil 20corresponding to those of FIGS. 2A to 2G, and the curves correspondingto those of FIG. 3 are identified by the same reference numerals butwith primes added thereto, for example, as at 2A and 2G.

As described above, in accordance with the present invention thedeflection coil 20 is formed with the typical cross section shown inFIG. 7 and in which the cross section area is selected to be the same asthat of the well known D cos"0 winding. Thus, the distribution of theconductor windings of the present invention becomes similar to that ofthe prior art and the similar deflection characteristics can beobtained.

Further, with the present invention the coil winding apparatus 30, whichis used to manufacture the deflection coil 20, is so formed that thecenter or working axes of the inner and outer surfaces 26 and 27 of themale and female members 30A and 30B of the coil winding apparatus 30 canbe fixed at the intersection of the reference X-and Y-axes. As a result,the inner surface 27 of the female member 30B is, especially, easily andprecisely formed. Further, when the distortion such as the pincushion,misconvergence or the like is to be improved, it is sufficient to merelyincrease the ratio between the angles 6 and 8,, It will be apparentthat, when a plurality of deflection coils 20 are made, there is noscattering in deflection characteristics, that is, a plurality ofdeflection coils 20 which have the same characteristics can be easilymanufactured.

It will be apparent that many modifications and variations can beeffected in the above described embodiment of the invention by oneskilled in the art'without departing from the spirit and scope of theinvention as defined in the appended claims.

I claim as my invention:

1. A saddle type deflection coil for a cathode ray tube havingcross-sections in planes perpendicular to a first axis corresponding tothe longitudinal central axis of said cathode ray tube and each of whichconsists of a pair of half sectional portions substantially symmetricalwith reference to a second axis lying in the respective plane and beingperpendicular to said first axis, each of said half sectional portionsof each cross-section including:

a. an outer curved margin defined by an arc ofa circle with a center ata point on said first axis;

b. an inner margin having a curved part formed by an arc of anothercircle with a center at said point on said first axis and a straightpart extending parallel with said second axis from said curved part; and

c. a pair of connecting margins between the adjacent ends of said outerand inner margins.

2. A saddle type deflection coil according to claim I, wherein thediameters of said circles of which arcs define said outer curved marginand said curved part of the inner margin increase gradually inaccordance with the positioning of the respective plane along said firstaxis from the rear to the front of the deflection coil.

3. A saddle type deflection coil according to claim 2, wherein thelength of said straight part of the inner margin is gradually increasedwith the increase in the diameter of said circle having the arc whichdefines said curved part of the inner margin.

4. A saddle type deflection coil according to claim 1, wherein each ofsaid cross-sections has an area equal to that of Dcos"6 deflection coilat a corresponding location along the latters longitudinal central axis.

1. A saddle type deflection coil for a cathode ray tube havingcross-sections in planes perpendicular to a first axis corresponding tothe longitudinal central axis of said cathode ray tube and each of whichconsists of a pair of half sectional portions substantially symmetricalwith reference to a second axis lying in the respective plane and beingperpendicular to said first axis, each of said half sectional portionsof each cross-section including: a. an outer curved margin defined by anarc of a circle with a center at a point on said first axis; b. an innermargin having a curved part formed by an arc of another circle with acenter at said point on said first axis and a straight part extendingparallel with said second axis from said curved part; and c. a pair ofconnecting margins between the adjacent ends of said outer and innermargins.
 2. A saddle type deflection coil accOrding to claim 1, whereinthe diameters of said circles of which arcs define said outer curvedmargin and said curved part of the inner margin increase gradually inaccordance with the positioning of the respective plane along said firstaxis from the rear to the front of the deflection coil.
 3. A saddle typedeflection coil according to claim 2, wherein the length of saidstraight part of the inner margin is gradually increased with theincrease in the diameter of said circle having the arc which definessaid curved part of the inner margin.
 4. A saddle type deflection coilaccording to claim 1, wherein each of said cross-sections has an areaequal to that of Dcosn theta deflection coil at a corresponding locationalong the latter''s longitudinal central axis.